Sighting apparatus for ordnance.



M 9 m Z M. y k m m U] D M A. T. DAWSON & G. T. BUGKHAM.

SIGHTING APPARATUS FOR OB-DNANGE APPLIUATION FILED MAY 22, 1908.922,398.

IINITE STATES PATENT erron- ARTHUR TREVOR DAWSON AND GEORGE THOMASBUOKHAM, OF WESTMINSTER, LONDON,

ENGLAND, ASSIGNORS TO VICKERS SONS & MAXIM, LIMITED, OF WESTMINSTER,ENG- LAND.

SIGHTING APPARATUS FOR ORDINANCE.

Original application filed October 23, 1907, Serial No. 398,717.

Patented May 18, 1909.

Serial No. 43%,231.

To all whom it may concern:

Be it known that we, ARTHUR TREVOR Dawson, lieutenant Royal Navy,director and superintendent of Ordnance Works, and Gnoncn norms BUCKHAM,engineer, both subjects of the King of Great Britain, residing at 32Victoria street, Westminster, in the county of London, England, haveinvented certain new and useful Improvements relating to SightingApparatus for Ordnance, of which the following is a specification.

This invention relates to sighting apparatus of the kind in which thereis a range dial and a pointer so arranged that in imparting angulardisplacement of the dial relatively to the pointer the proper elevationwill be given to the sight to accord with a particular range.

.Ve have already devised sighting apparatus in which a graduated dial ismoved by hand gearing relatively to the pointer for setting the sightfor different ranges, means being provided whereby in the act of settingthe range dial relatively to a pointer a correction will beautomatically made to compensate for alterations in the muzzle velocityand changes in the temperature of the charges by changing the positionof the pointer, so that in setting the range dial a greater or lessangular movement will be imparted to the dial in bringing a particulargraduation or mark thereon into coincidence with the pointer. Thesecompensating means we term a calibrating device.

It is the chief object of our resent invention to modify theconstruction of the said calibrating device.

Our present invention is particularly, although not exclusively,intended for use with duplex sights of the well known crossconnectedkind.

WVe will describe our invention with reference to the accompanyingdrawings in vation of the apparatus with the hinged,

sight bar and the sight proper removed; Fig. a. vertical section takenapproximately on the line 38 of Fig. l, and Fig. 3 a detail of theapparatus to an enlarged scale.

B is the pointer which is carried in a guide or frame B, and whichengages with a spiral groove a formed in the face of the range dial A,so that when the dial is revolved the pointer will move radially overthe face of the same. The said frame 13 is connected to a radial arm Bwhich is coaxially arranged with respect to the range dial A so as to befree to move angularly about the axis thereof.

The calibrating device comprises the cam or spiral groove a formed on orin the rear face of the range dial for actuating the roller (Z situatedat the end of one arm (Z of the bell-crank lever which is adapted toswing about an axis or bearing (Z carried by a bracket (5". The otherarm (Z of said bell crank lever has the sliding or adjustable block clwhich is adapted to be shifted and secured in any desired position onthis arm. This arm bears I temperature curves (Fig. 3) which arecarefully calculated for enabling the block (Z to be set in the properposition thereon as required for the change in charge temperature. Theradial arm B carrying the said angularly adjustable pointer frame B isprovided with a second arm or extension B connected by means of the linkor rod (Z with the sliding block (P. The said block is also providedwith the adjustable piece or pointer cl" working adjacent to a graduatedscale on the block for enabling the said adjustable piece cl" to besetby the actuation of the milled head (Z in the proper position foreffecting the corrections required for the change in muzzle velocity.

T 0 correct for muzzle velocity and charge temperature the member (F isfirst set to the muzzle velocity scale and then the sliding block (I ismoved along the arm (Z until an index on the member (Z touches therequired temperature curve.

Vhen the range dial is actuated by the hand gear A in the ordinarymanner to bring the desired graduation thereon into correspondence withthe pointer B,the aforesaid cam or spiral groove a also imparts movementto the bell crank lever (Z (Z This bell crank lever in turn impartsangular movement to the pointer frame B through the said connecting link(Z and the radial arm B carrying the pointer frame, to an en'- tentdepending upon the position of the said sliding block (Z on the arm (Zof the bell crank lever, and the degree of rotation imparted to therange dial by the hand gear. -f the block is moved inward toward thepivot (Z of the bell crank lever, so as to bring the center of thecontiguous end of the connecting link (Z into coincidence with thecenter of the pivot d of the bell crank lever, the motion imparted tothe bell crank lever by the aforesaid dial cam or spiral groove a willnot affect the position of the pointer frame B. If, however, the slidingblock be moved outward or away from the pivot (Z of the bell cranklever, he motion imparted to the latter by the dial cam or spiral groovewill be transmitted to the pointer frame through the said link (Z, to agreater or less extentaccording to the distance the sliding block hasbeen shifted from the pivot of the hell crank lever. Thus the elevationgiven to the sight during the movement of the range dial in bringing thedesired graduation into correspondence with the pointer will beincreased to the extent to which the pointer frame is set by thecalibrating device so as to automatically effect the requisitecorrection for the fall in themuzzle velocity and the change in chargetemperature. Fig. 3 shows the calibrating device set for a muzzlevelocity of 763 meter seconds anda charge temperature of 27 degreescentigrade. The said spiral groove a that imparts motion to thecalibrating device is preferably formed in a disk (4 to which the dialit may be attached by means of our usual clamping ring (4 having acircular series of keyhole slots that operate in coniunction withflanged pins or screws projecting from the said disk, so that byimparting angular movement to the clamping ring the dial can be readilydisconnected. The said pointer may be secured to the radial arm by ourusual clamping nut (/1 which when slightly slackened permits the pointerframe to move radially outward until clear of the nut a, whereupon itcan be detached.

What we claim and desire to secure by Letters Patent of the UnitedStates is In sighting apparatus for guns, the combination with the rangedial and its index or pointer, of hand actuated means for setting therange dial with respect to the pointer and changing the elevation of thesights, means for causing said pointer to move radially across the faceof the range dial during the setting of the latter, a double armedor'bell crank lever of which one arm or member engages with a cam orspiral groove of the range dial, an adjustable piece mounted on theother arm or member of the said lever and connected with the pointer bymeans whereby the angular position of the pointer will be varied inaccordance with the position of the adjustable piece and the degree ofmotion imparted to the range dial during the setting of the sights bythe hand actuated means.

In testimony whereof we have hereunto set our hands in the presence oftwo subscribing witnesses this eighth day of Hay, 1908.

ARTHUR TREVOR DAWSON. GEORGE THOMAS BUCKHAlll. lVitnesses HENRY KING,Ariel-11E H. NIoI-roLs.

